Hitherto, sheet molding compound (SMC) has been widely used as the forming material for manufacturing reinforced plastic products such as bath tubs. This SMC is prepared by mixing liquid unsaturated polyester resin and reinforcing material such as chopped strand, filler, and thickener, and forming in a sheet by decreasing its moisture content thereby becoming adhesive. Accordingly, as shown in FIG. 26 and FIG. 27, the SMC 10 is usually formed in an SMC sheet 12 covering its upper surface and lower surface with a polyethylene or other parting film 11 broader than the width of the SMC 10, and is wound around a core tube 14 to be formed in an SMC roll 13, or folded in a pleated form which is not particularly shown.
Forming of a reinforced plastic product from such SMC comprises the step of cutting out a necessary portion for one forming from the SMC sheet, feeding the cut segment of SMC into the forming machine, heating and pressurizing the SMC segment in the machine, and curing.
In this process, until the SMC is supplied to the forming machine, the SMC undergoes a step of peeling off the upper and lower parting films from the SMC sheet 12 let off from the SMC roll 13 and cutting the SMC to a specific length, a step of transferring the obtained segment of SMC to a weighing device, a step of weighing to see if the weight of the SMC segment has reached a specific weight necessary for forming, and a step of charging the weighed segment of SMC into the forming machine.
In the step of cutting the SMC sheet, conventionally, a sheet cutter 800 as shown in FIG. 28 has been used. The sheet cutter 800 comprises a receiving stand 801 for rotatably pivoting the core tube 14 of the SMC roll 13, a pair of pinch rolls 802, 802 for pinching the SMC sheet 12 supported and pulled out from the receiving stand 801 from above and beneath and letting off to the downstream side, take-up rolls 803, 803 for taking up the peeled parting films 11, 11 at the let-off side of the pinch rolls 802, 802, and a cutting blade 804 for cutting the SMC in the widthwise direction (the direction orthogonal to the sheet of paper in FIG. 28). The SMC sheet 12 is pinched by the upper and lower pinch rolls 802, 802, and is let off to the downstream side as they are simultaneously rotated and driven in mutually opposite directions, while the cutting blade 804 fixed to a holder 805 is run in the widthwise direction of the SMC 10 to cut it sequentially into segments 15.
In FIG. 28, meanwhile, numeral 806 denotes a connection table, 807 is a guide moll for leading the SMC sheet 12 onto the connection table 806, and 900 is a cut sheet conveyor for conveying the segment 15 of the SMC 10 supplied from the sheet cutter 800 to a specific position.
Besides, in the step of transferring the SMC segment obtained by the sheet cutter to the weighing device, handling is difficult because the SMC is adhesive, and therefore since the segment cannot be sent into the specified position of the weighing device without damaging by general conveying equipment, conventionally, the segment of SMC was manually transferred from the cut sheet conveyor to the weighing device.
In the weighing step, the weight of the SMC supplied to the forming machine must be accurately determined according to the reinforced plastic product to be formed, or the reinforced plastic products cannot be manufactured in specified weight balance. For this purpose, for example, a weighing method was purposed in the Japanese Laid-Open Patent (KOKAI) No. H02-121811. That is, the SMC necessary for one product is successively cut in specific length, and each cut segment of SMC is weighed, while the weights are cumulatively added up, and in the final cutting step, the cutting length of the final segment is increased or decreased depending on the hitherto total weight of segments and the weight necessary for one product.
In the charging step, considering the fluidity of the SMC in the forming die in the forming machine, the SMC segment must be correctly put into the predetermined charging position of the forming die. However, since it is hard to handle the SMC, conventionally, the SMC was manually charged into the forming die. Recently, to improve this point, for example, it is proposed in the Japanese Patent Publication (KOKOKU) No. H02-36371 which relates to handling technique for skewering stacked pieces of SMC by rotating a spiral tool, conveying up to the forming die in this state, and rotating the tool reversely on the forming die to put in. It is also known to charge the SMC segments into the forming die by using a telescopic conveyor.
Thus, the procedure for feeding the SMC into the forming machine comprises complicated steps, and a part of the steps still depends on manual operation, and therefore the productivity is inferior. Besides, manual handling of SMC requires hard labor and is heavy in burden of workers because even a segment of SMC is very heavy. In addition, adverse effects on human health by the reinforcing materials contained in the SMC must be considered. In this background there is a keen demand fop an automatic feeder of SMC fully automating all these steps.
For fully automating all steps, the conventional devices may be used in the already automated steps, but each device has its own problems as discussed below, and they may not be employed directly.
More specifically, in the sheet cutter 800 used in the step of cutting the SMC sheet, the parting films 11, 11 cannot be neatly peeled off the SMC sheet 12. That is, if there is any local thick part in the resin paste drawn out duping storage of the roll on the SMC sheet 12, or deviated crease or folding of the end portion in the parting film, if attempted to peel off the parting films 11, 11 along the pinch rolls 802, 802, the SMC 10 may be taken, up together with the parting films 11, 11.
In the conventional weighing method in the weighing step, the weight of each segment is weighed and added up to stack up the segments of the SMC fop one product, and the errors of the weighing devices may be accumulated to increase, and a large weighing error may result in. When feeding the final segment, the error becomes large due to fluctuations of the unit length weight, and the weight precision is lowered.
In the SMC charging mechanism mentioned about in the charging step, since the SMC segments are skewered by a detachable tool, and penetration holes are formed in the segments, and they may cause pinholes in the products, and the product defective rate may be increased. In the telescopic conveyor, when the charging height becomes higher, it is difficult to charge the segment precisely into the specified position of the forming die, which is another factor to raise the product defective rate.
In the light of the above problems of the conventional devices, it is hence a primary object of the invention to present an automatic feeder of adhesive sheet material capable of automating fully in all steps from cutting to charging.